I think you should change the visual verification to something a bit easier.
The first 2 times I got it wrong.
I clicked on "listen to letters" and still got it wrong. (it's hard to differentiate z, g, d. etc.)
I turned on accessibility options, magnification, and could not make out a letter,
I put on my reading glasses. still no luck
I clicked on direct link in listen to letters, and by having it repeat over and over, and magnified 2 times, i was able to make it out.